Overview:

Accurate mass compound identification typically requires HiRes MS systems at significant costs. Unfortunately, even top-of-the-line HiRes MS with ≤1ppm mass accuracy can have difficulty in the determination of elemental compositions for compounds with m/z ≥ 300. The use of reliable isotope information can help in these situations. Taking full advantage of the exact isotope information requires attaining another important metric, called spectral accuracy. In order to achieve high spectral accuracy suitable and useful for elemental composition determination, a novel MS calibration has been developed, which not only calibrates m/z but more importantly the MS peak shape.

Through such a novel calibration process, high enough mass accuracy (≤10mDa) combined with high spectral accuracy (≥98.0%) enables formula determination even on a single or triple quadrupole MS system. When such an approach is applied to HiRes MS systems, ≥95% of the incorrect elemental compositions obtained from the use of mass accuracy alone could be eliminated from consideration, significantly simplifying compound identification task on sector, TOF, Orbitrap, or FT ICR MS systems.

Subject Areas Covered in Presentation:

• Basics and challenges of elemental composition determination

• Importance of spectral accuracy vs mass accuracy

• A novel MS calibration enabling formula ID on quadrupole while significantly improving HiRes MS